1. Field of the Invention
The invention refers to a process for controlling the movement of an universally swivellable cutting arm of a partial cut cutting machine comprising a first hydraulic drive for lifting and lowering the cutting arm and a second hydraulic drive for swivelling the cutting arm transversely relative to the lifting and lowering direction as well as to a device for performing this process.
2. Description of the Prior Art
Partial cut cutting machines equipped with a universally swivellable cutting arm frequently comprise hydraulic cylinder-piston-aggregates for lifting and lowering the cutting arm in substantial vertical direction as well as a swivel drive which may, for example, be obtained by the engagement of a hydraulically actuated toothed rack in a toothed wheel of a traversing gear. In this case, swivelling of the cutting arm is, as a rule, effected about an axis extending essentially in normal direction relative to the chassis and on account of this traversing gear also the hydraulic cylinder-piston-aggregates for lifting and lowering the cutting arm are swivelled about this axis substantially extending in vertical direction. The cutting arm can thus be lifted or lowered in any horizontally swivelled position.
For cutting profiles with partial cut cutting machines having provided on the free end of the cutting arm cutting heads rotatably supported for rotation around an axis transversely extending relative to the longitudinal axis of the cutting arm, the advancing direction is most frequently selected in direction of the axis of rotation of the cutting head. After having reached the nominal profile, the cutting head is lifted or lowered for the so-called preselected depth of cut, whereupon the advancing movement is effected in the opposite direction and again in an essentially horizontal direction. On account of the construction of such cutting machines, there remains a rib of rock between both cutting heads arranged on the free end of the cutting arm when lifting or lowering the cutting arm for obtaining the new preselected depth of cut. This rib must subsequently be broken away when swivelling the cutting arm in a substantially horizontal direction. In dependence on the properties of the rock and on the construction of the machine, this rib may be too great for being easily broken away by swivelling the cutting arm. In these cases, swiyelling of the cutting arm in its new position is only possible with difficulties, and laboursome manual operations are required for crushing this rib to be then in the position to continue cutting work in the opposite direction.